Non-anthocyanin phenolic compounds and antioxidant activity of beverages obtained by gluconic fermentation of strawberry

• 43 non-anthocyanin phenols identified in strawberry and gluconic fermented beverages.
• 5 of them for the first time: kaempferol neohesperidoside, and dihydrokaempferol hexoside.
• And also: monogalloyl diglucose, hydroxy feruroyl hexose, and (−)-chicoric acid
• Gluconic fermentation maintains the antioxidant activity of strawberry.

Strawberry is widely harvested in Spain. It is a highly perishable fruit and surplus production may be used to produce innovative foods. This paper studies the influence of gluconic fermentation by Gluconobacter japonicus on the non-anthocyanin content and antioxidant activity of strawberry. A total of 43 non-anthocyanin phenolic compounds were identified. To the best of our knowledge, this paper reports five compounds for the first time in strawberry and its derivatives, tentatively identified as: monogalloyl diglucose, 5-hydroxy feruloyl hexose, dihydrokaempferol hexoside, kaempferol neohesperidoside and (−)chicoric acid. It was further observed that gluconic fermentation leaves in vitro antioxidant activity practically unchanged.Gluconic fermentation by Gluconobacter japonicus can be considered a potential tool for producing fermented beverages. It transforms glucose into gluconic acid, which allows diabetics to consume the drink, while maintaining bioactive compound concentration and antioxidant activity.Industrial relevanceAs strawberry is a highly perishable product, fruits spoil quickly, leading to substantial economic losses. Therefore, the transformation of strawberry surplus into new, longer-lasting products is a financially worthwhile solution for the industry and producers. Our gluconic beverages were elaborated by traditional process using exclusively strawberry as raw material easily transferable to industrial scale. The main innovation aspect relies on developing an innovative product, aiming to fulfill consumers demand who are permanently seeking for different taste and flavors. At the same time its composition in sugars (non-glucose, original fructose content) makes these products very suitable for dietetic purposes.